1. Field of the Invention
The present invention relates to an organic light-emitting diode (OLED) display device and a method for driving the OLED display device. More particularly, the present invention relates to an OLED display device that may have an increased lifetime and a method for driving the OLED display device.
2. Discussion of the Background
Generally, a unit pixel of an organic light-emitting diode (OLED) display device includes a switching transistor TRs, a storage capacitor CST, a driving transistor TRd, and an organic electroluminescence (EL) element. The switching transistor TRs switches a data signal in response to a gate signal. The storage capacitor CST stores the data signal during one frame interval. The driving transistor TRd provides the EL element with a bias voltage corresponding to the data signal. The EL element is electrically connected to a common voltage, and it emits light in response to a current corresponding to the bias voltage that is transferred from the driving transistor TRd.
When the same polarity data voltage is continuously applied to a gate of an amorphous silicon thin-film transistor (a-Si TFT), the a-Si TFT's output characteristics gradually deteriorate (or suffer gradual failure). That is, with a driving transistor TRd that controls an output current in response to the gate voltage, when the same polarity data voltage (i.e., a positive polarity voltage with respect to a common voltage Vcom) is applied to the gate of the driving transistor TRd for a long time, the a-Si TFT's output characteristics gradually deteriorate.
In order to prevent deterioration of the a-Si TFT, during an interval in which the EL element is not emitting light, a signal having a different polarity from a polarity of the data signal may be applied to the driving transistor TRd. However, including the additional interval to apply the signal having the different polarity voltage may not be desirable.